Railway traffic controlling apparatus



Oct. 6, 1936. E. M. ALLEN ET AL RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Dec.

29, 1930 2 Sheets-Sheet 1 INVENTORS. E. M, H I Ian, G. fi.Brooks, flg Q; QM MATTORNEY.

I QLE 1 Oct. 6, 1936. E. M. ALLEN ET AL RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Dec. 29, 1930 2 Sheets-Sheet 2 INVENTORSH 5/4. Allen,

Gfl. Breaks,

' ATTORNEY.

Patented Oct. 6, 1936 UNITED STATES RAILWAY TRAFFIC CONTROLLING APPARATUS Earl M. Allen,

Edgewood, Pa., and Charles A.

Brooks, Forest Hills, N. Y., assignors to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application December 29 1930, Serial No. 505,327

Renewed March 21, 1935 11 Claims.

Our invention relates to railway traffic controlling apparatus for governing trafiic over a stretch of railway track, and more particularly it relates to that class of apparatus whereby a control is exercised over the movements of a railway switch and its associated signals from a remote point;

Our invention is an improvement upon that which is disclosed and claimed in a copending application of common ownership, Serial No. 505,328, filed on the same day, December 29, 1930, by Earl M. Allen, Charles A. Brooks and Howard A. Thompson, for Railway traffic controlling apparatus.

We will describe one form of apparatus embodying our invention, and will then point out the novel features thereof in claims.

Figs. 1 and 2, when placed end to end with Fig. l on the left, form a diagrammatic view showing one form of apparatus embodying our invention when applied to a stretch of railway that includes a single switch and its associated signals.

Referring to the drawings, a railway switch designated by the reference character SW is operated by any standard type of switch machine shown in Fig.1 by a symbol which is designated by the reference character SM. The operating circuits for the switch machine SM are not shown in the drawings, as they form no part of our invention and they may be any one of the several types well known to the art. In this instance the control of the switch machine SW from a remote point or central office is by means of code relays SK and 6Y to be referred to later. It will be understood however that our invention is not limited to this one system 'of centralized control but that other methods may be employed; for example the control may be by means of controllers operated by levers of a tower machine, or the switch may be controlled automatically by traffic conditions.

The insulated rail joints 3 divide the traflic rails I and 2 of the stretch of railway into the track sections L3T and L2T, IT, RZT and R3T. The track sections L3T, L2T, R3T and R2T will be referred to as approach track sections, while the section IT will be referred to as a detector track section. -Each track section of our invention is provided with the customary track circuit which includes a source of current and a track relay connected to the trafiic rails in the usual manner as will be readily observed by an inspection of the Figs. 1 and 2.

The wayside signals for governing trafiic from the right to the left in the Figs. 1 and 2 are designated by the reference characters L2 and L3 and the signals governing traffic from the left to the right are designated by the reference characters R2, R3 and R2d. These signals may be of any of the well known types but are here shown as color light signals of the Searchlight type such as disclosed and claimed in United States Letters Patent Reissue No. 14,940 granted to E. J. Blake. The signal L2 is provided with two mechanisms indicated by the reference characters a and b, each mechanism consisting of a motor operating relay which includes two windings 4 and 5. The

. Winding 4 of mechanism a of L2 is constantly supplied with power from a convenient source of current not shown in the figures. Throughout the figures, the positive terminal of the source of power is designated by the reference character B and the negative terminal is designated by the reference character C. With the winding 5 of the mechanism a of signal L2 energized in a manner to be later described, the signal displays a proceed signal. With either winding 4 or 5 deprived of power, the signal displays a stop signal. This mechanism a controls two circuit controllers 6 and 7 in such a manner that when the signal is set to display a stop signal, the controllers 6 and! are in engagement with the lower fixed contracts 8 and 9 respectively and when set to display a proceed signal, the controller 6 remains in the same position while the controller 1 is shifted to engage with the upper contact IO. The mechanism b of L2 is of the same construction as that of mechanism a and controls two circuit controllers in like manner. 1

The mechanism a, of the signal R2 is similar to that of a for the signal L2 while the signal b of R2 is a fixed signal displaying stop only. The signal R212 governs traffic moving from the siding to the main line and its mechanism at is similar to that of a for L2 described above. The mechanism for the signal L3 is the same as that of a of L2 already described except that it is arranged to assume three positions. Its winding 4 is continuously energized and then when the winding 5 is energized with current of one polarity, the signal displays a caution signal while with the winding 5 energized with current of the reverse polarity, the signal is set to display a proceed signal. When the signal L3 is set to display a proceed signal its controller 1 is shifted to engage the top contact l0 and when the signal is set to display a caution signal the controller 1 remains in engagement with low contact 8 and the controller 6 is shifted to engage the contact H as shown in Fig. 2. The sigsame as the signal L3 and needs no further description. adaptedto the use of any standard type of signals as the operating circuits for .the signals form no part of our invention.

In order to simplifythe figures somewhat and to make the circuits easier to understand, we

have in a number of instances, especially in the case of the signal circuit control network, placed a circuit controlling armature in a location in the figures that is not adjacent to the relay that controls the armature. In all such instances, the armature is designated by a reference character with an exponent corresponding to the con trolling relay and all such armatures are shown in the position corresponding to the normal cone dition of the relay. For illustration the circuit controlling armature designated by the reference character 2c in Fig. l is operated by the track relay TR of Fig. 2 and the armature 20 normally occupies its raised position as shown, as. the relay TB is normally energized.

The code relays BY, 6X, 'IY and 1X may be controlled from a central office and are shown as being located at the switch on a panel that is indicated by a dotted line. As the controlling circuits for these code relays also form no. part of our invention, they are omitted from the figure for the sake of clearness. For a description of our invention, it is deemed suflicient to say that these ,7 code relays may be selectively energized and deenergized from some central office and when energized they lift their armatures into engagement with front contacts and when deenergized the armatures drop into engagement with back contacts.

The circuit controllers I2, 13 and 14- of Fig. 1 are operated by the switch SW, the connection being indicated by a dotted line. Each controller occupies an upper position in the'Fig. 1 as shown by a solid line when the switch is set for the main track while each controller is shifted to alower position as indicated by a dotted line whenthe switch is set fora movement to the siding. I

The switch control relay W is preferably a direct current polarized relay. This relay when energized with normal polarity of current moves its polarized armatures to a normal position to select the normaloperating circuits (not shown) for the switch machine SM to position the switch for the main line. When relay W is energized with reverse polarity of current its polarized armatures are moved to a reverse position to select the reverse operating circuits (not shown) for the switch machine SMto position the switch forthe siding. In the Fig. 1 the normal position of the armatures of relay'W is the left-hand position-that is, the positionshown in the Fig. 1 andthe reverse position is the right-hand position-r theposition .oppositethat shown in the Fig. 1. The switchcontrol relayW is controlled by means of the code relays BY and 6X. With 7 the normal code relay 6X selected and its armature l-raised into engagement with its front contact then current is supplied .to the relay W from the positive terminal B through the back contact; of the, armature l8 of the code relay EY deenergized, armature l5 of the relay'GX raised into engagement with its front contact, as the relay is now energized, wire l9, armature 2! of the trackrelay TR, wire. 22, armature 23 of an approachlockingrelay LM to be later described, wire 24, armature 25 of a second As stated above, our invention isapproach locking relay RM, wire 26, winding of relay W, wire 21, armature l6 of the relay 6X, armature ll of relay BY and to the negative terminal C. The polarity of the current supplied by the above traced circuit positions the armatures of relay W in the left-hand position and thus brings about the normal position of the switch SW. In the event the code relay :BY is selected so that relay BY is energized and relay 6X deenergized, it is apparent from an inspection of the Fig. 2 that the current supplied by the above traced circuit for the relay W flows in the winding of the relay in a direction reverse I to that first mentioned and thereby position its armatures in the right-hand position to bring about the reverse position of the switch.

The switch repeater relay KR is preferably a direct current polarized relay and is controlled jointly by the switch SW and the switch control relay W. With relay W normal and the switch set normal, then current. is supplied to the relay KR. from positive terminal B through controller l2, wire 28, winding of relay KR, wire 29, armature 30, wire 3|, controller I4, and to the negative terminal 0'. With relay W and the switch SW each in the reverse positionthen the relay KR is supplied with current of a reverse polarity by a circuit that extends from positive terminal B through controller I3, wire 32, armature 30, reversed, wire 29, winding of KR, wire 28, controller I2 and to the negative terminal C. When relay KR is energized under normal position ofthe switch SW, its polarized armatures occupy the left-hand position, while when the relay KR is energized with the switch SW reversed, the position of its polarized armatures is the right-hand position. It is appar-' ent that with the relay KR energized with either polarity of current that its neutral armatures are raised into engagement with their front contacts. V

The direction of trafiic is'respectively selected by two trafiic-governing directional relays RH and LH. The relay RH is associated with trafiic from the left to the right and the relay LH is associated with trafiic-from the right .to the left. A code that selects the relays GK and HI brings about the normal position of the switch SW for armature 33 of the relay IY, back contact of the armature34 of the relay 1X, wire 35,back contact of the armature 36 of an approach control relay RA to be shortly described, wire 31, back contact of armature 38'LH of the opposing directional relay- LH, wire 39, winding of relay RH, wire 40, armature 20 of the track relay TR, wire 4|, neutral armature 42 of relay KR, polarized armature 43, wire 44, front contact of armature 45 of relay SK and to the negative terminal C. Once the relay RH is energized by the above circuit, there. is closed a stick circuit that branches from the wire 4| through the front contact of its own armature 46 and to the negative terminal C. Also for purposes to be shortly pointed out, a branch path is provided around the back con tact 36 of the approach control relay RA which path includes a wire 51 branching from thewire 35, reverse contact of armature 58 of the relay KR and wire 53 to wire 3'1. I i

In the event the controlling code selects the code relays GK and 1X then as soon as the switch SW is positioned for the main line, a circuit is established for the directional relay LH that may be traced from the positive terminal B through armature 33 of relay IY in engagement with its back contact, armature 4'! of the relay IX in engagement with its front contact, wire 48, back 1 contact 49 of the approach control relay LA shortly to be described, wire 50, back contact of the amature 5I wire 52, windingof relay LH, wire 53, wire 40, armature m wire 4I, armature 42, polarized armature 43, wire 44, armature and to the negative terminal C. Once the relay LH is energized, there is closed a stick circuit that branches from the wire 4I through the front contact of its armature 54 and to the negative terminal C.

It is to be noted that in the case of relay RH that its circuit is held open at the back contact of the armature 36 of the approach control relay RA even after the controlling code has selected the code relays GK and HI, and also that the circuit forthe relay LH is held open at the back contact of the armature 49 of the approach control relay LA even after the controlling code has selected the code relays GK and IX. In the event the code relaysBY and IX are selected so that the switch SW is reversed and the armature 43 of the switch repeater relay KR reversed to its right-hand position, it is to be noted that the above traced circuit for relay LH then extends from the reverse contact of the armature 43 along the wire 55, armature 56 of relay BY and to the negative terminal C. In like manner when the reverse switch code relay 6Y and the signal code relay'IX are selected, the circuit for the directional relay RH is completed from the reverse position of armature 43 of relay KR by wire 55 and the armature 56 t0 the negative terminal C, and also in this case the open back contact of the armature 36 of the approach control relay RA is bridged by the path through the reverse position of the armature 58 of the switch repeater relay KR.

To sum up thus far, with the switch set for the main line, the directional relays RH or LH are controlled by the code relays and are approach energized by means of a back contact of the respective approach control relay RA or LA, and that with the switch set for the siding the reverse position of the polarized armature 58 annuls the approach energizing of the relay RH.

Each direction of traffic is provided with an approach control relay and an approach locking,

relay; The approach control relay RA associated with traffic from the left to the right is normally energized by a circuit extending from positive terminal B at the signal location R3 through the armature 84 of the track relay R3TR, armature 85 of the track relay RZ'IR, wire 86, winding of relay RA and to the negative terminal C. The approach control relay LA associated with trafiic from the right to the left is normally energized by current supplied by a circuit from the positive terminal B at the signal location L3 through the armature 81 of the track relay L3TR, armature 88 of the track'relay LZTR, wire 89, winding of relay LA and to the negative terminal C.

The approach locking relay RM associated with trallic from the left to the right is normally held energized by a stick circuit that can be traced from the positive terminal B at signal location R3 through the controller 6, contact 9, either contact 8 or I0, controller I, indicating that signal R3 is either at stop or caution position, wire 90, armature SI of a relay RGP associated with the signal R2 as will be later described, wire 92, back contact of the armature 93 of directional relay armature 98, Wire 99, front contact of the armature I 00 of the approachrcontrol relay RA, wire IOI, winding of'relay RM and to the negative terminal C. This pick-up circuit for the relay RM has the branch path that extends from the wire'96 along wire I02, front contact, of the armature I03 of a time element relay TE to be later described, wire I04 to the wire IM and then as before traced.

The approach locking relay LM associated with traffic from the right to the left is normally held energized by a stick circuit that is similar to that described for the relay RM and which circuit extends from the positive terminal B at the signal location L3 through controller 6, either contact II or 9, contact 8, controller I, indicating signal L3 is either at stop or caution position, wire I05, armature I06 of a relay LGP associated with the signal L2, wire I0'I, back contact of the armature I08 of the relay LH, wire I09, front contact of its own armature IIO, winding of the relay LM and to the negative terminal C. This approach locking relay LM is provided with a pick-up circuit that extends from positive terminal B along the same circuit as before traced up to the wire I09 and from that point it extends along wire II I, front contact of the armature II2 of the approach control relay LA, wire II3, winding of the relay LM and to the negative terminal C. Branching around the armature IIZ of the relay LA is a path that includes wire II 4, front contact of the armature II5 of the time element relay TE,and'wire II6 to the wire II3. I

Associated with the approach locking relays RM and LM is a time element relay TE. This time element relayTE may be of any of the well known types and in this instant, it is normally deenergized and will close the front contacts of its armatures I03 and-I I5 some predetermined time interval after the energizing circuit has been closed. The time interval should be enough to allow a train to'be over the switch and gone or to allow the train ,to come to a stop before it reaches the signal.

When trafiic is from the left to the right the circuit for relay TE extends from positive terminal B at signal R3 through controller 6, con-tact 9, controller I in engagement with either in engagement with either contact 9 or I I, co'ntact 8, controller 1, wire I05, armature I06, wire I01, back contact of armature I08, wire I09, back contact of armature H0, wire I20, wire 1, armature IIB wire I I9, winding of TE and to the negative terminal C.

The directional relays RH and LH govern the controlling circuits of the wayside signals. Referring first to the relay RH which controls the signals R2 and RM, we find that a circuit for the winding 5 of the mechanism a of R2 extends from the positive terminal B through a circuit network that includes the armature 50 of the armature 62 of the time element device TE, armature 63 jfront contact'of the armature 1 B l of the relay RI-L'armature 65 back conrelay LGP, back contact'of armature GI of op-- posing directional relay LI-L-back contact of the tact of the armature 66 polarized armature 61, wire 68, winding 5 of the mechanism a. of

7 tact of the armature 61 along wire ll, winding-5 of the mechanism do f the signal R2d, Wires 12 and 69; armature .10 of relay RH and to the negative terminal C. Under this condition the mechanism d of signal R2d is op-' erated to display 2. proceed signal. In connection with the operation of'the mechanism d of'RZd, an inspection of the Fig. l discloses the fact that to energize the winding 4 ofthe mechanism d, it requires that the mechanism a occupy a stop position so that'the controllers 6 and I of mechanism a are in engagement with their respective contacts 8 and 9.-

Referring next to the relay LI-I which governs the operation of the signal L2, with the relay LH energized, we find a circuit extends from thepositive terminal B through the circuit network 'that includes 'thearmature H back contact of the armature 64, neutral armature 63 armature 62 front contact of the armature BI asrelay LH is now' energized, back contact of the armature 'M of theapproach locking relay LM, armature 15; wire 16, armature 11 of the approach control relay RA, wire 18, winding 5 of the mechanism a of signal L2, wire I9, armature of the'relay LH and to the negative terminal C. -With :this circuit closed then the mechanismlal of signal L2 is operated to display 7 a proceed'signah In theeventthe switch'SW is set'forthe siding so that the armature l5 of the switch repeater relayKR is reversed, then the above traced circuit-extends from that point alongthe' wire Bl to the winding 5 of the mechanism b of signal L2, wires 82 and 19, armature 80 and to the negative terminal C. Under this condition where the switch SW is'reversed-and the relay LI-I energized, the mechanism 5 is set to displayaproceed signal to permit a movement to the siding. In connection with the operation of the mechanism 1) of the signal L2, it will 'beobserved from- Fig. 2, that the circuit for energizing the winding 4 of 1) includes the controllers 6and1of'the mechanism a in a stop position; r V

When the directional relay RH is energized and the switch SW set normalso that the mechanism a of'the' signal R2 is operated to a proceed position then controller 1 engages the contact I0 and a circuit is completed from positivefter minal B through-controller 6, contact '8; controller I, contact I0, wire 83, winding-of the relay RD and to the negative terminal C. The energizing of the relayrRD reverses the polarity of the current supplied to the winding 5 of the signal mechanism for signal R3 and this signal'is" moved froma'caution to the proceed position. In like manner when the switch is set normal and the directional relay-LH' is energized to supply Associated with the signal R2 is a normally en-' ergized relay RGP which has as its function the checking of the stop position of the signal mechanisms of R2 and R2d. The energizing circuit for the relay RGP passes through the stop position of the controllers of both the mechanisms a and d in series as will be r'eadily understood by an. inspection of the Fig. 1. Whenever either of these mechanisms a or d is operated from the stop position, then the circuit for the relay RGP is opened and that relay becomesdeenergized. The signal L2 is associated with a normally energized relay LGP-that is controlled by a circuit through the controllers of the mechanisms'a and b of the signal L2 in a manner similar to that referred to for the relay RGP; v 1

Having pointed out the several circuits and the diiferent apparatus that are included in our in-- vention we will now describe its operation. It

will be understood that all apparatus of the Figs.

, l and 2 is shown in its normal position. We

shall first assume that a controlling code selects the relays SK and 'IY. The selecting of the relay 6X results in the switch being positioned for the main line and the selecting of the relay lYresults in the circuit for the relay RH-being supplied with power. The circuit for the relay RHLhoW- ever is still held open at the back contact of the armature 36 of the approach control relay RA, and thus the signal R2 remains at stop even after the relays 1Y' and 6X have been energized.

Assuming. next that a train approaches from the left and enters the approach track section R3T, the shunting of the track relay R3TR by the train opens the circuit for the approach control relay RA and the deenergizing'of that relay drops its armature 36. Armature 36 being now in engagement with itsback contact, the circuit for the directional relay RI-I is completed andthat relay picks up, to supply current to the winding 5 of the mechanism a of the signal R2 through the front contacts of the armatures I0- and H The circuit for the winding 50f mechanism aremains open'however at the back contact of thearmature 66 of theapproach locking relay RM.

comes deenergized inasmuch as its pick-up circuit is now opened at the contact I00 of the: relay RA. The deenergizing of the relayRM permits armature 66 to engage its back contact and thus the circuit to the winding 5 of mechanism a is now closed and the signal R2 is set to display a proceed signal to the approaching train. The clearing of the signal R2 energizes the relay RD in the manner previously pointed out andthe signal R3 is set to display a proceed signal.

- In other words the apparatus of our invention provides that the clearing of the signal R2 -is jointly governed by the control exercised from some remote point such as a despatchers ofli'c'e,

' and by theapproaching train. It also assures that the approach control relay RA and the api proach locking relay RM have assumed their locking position against an operation of the switch 75 l SW before a proceed'signal can be displayed by the signal R2. r

As the train advances past the signal R2 and enters the detector track circuit, the shunting of the track relay TR to open armature 211 deenergizes the relay RH and the signal R2 assumes the stop position. As soon as the train vacates the approach track sections R3T and R2T, the approachcontrol relay RA-is reenergized. Relay RA on being reenergized closes the front contact of its armature 1'00 which is included in the pickup circuit of approach locking relay RM and this relay then is 'reenergized. The apparatus is thus restored to its normal condition. As pointed out earlier in the description, the energizing of the relay RH closes its stick circuit through the front contact of its armature 46. In the event it is desired to store a reverse switch movement by energizing code relay BY after the route above mentioned has been set up andthe signal R2 cleared by a train entering the approach track section, the energizing of the code relay BY to effect a reverse movement of the switch will not disturb the proceed position of the signal R2 as the relay'RH isheld energized by the stick circuit that includes its armature 46 Let'us next assume that the controlling code selects the relay GK and 1X so that the switch is 'set normal and current is supplied to the circuit for the relay LH through the front contact of the armature 41 of the relay TX. The circuit to the relay LH is held opened however at the back contact of the armature 49 of the approach control relay LA and thus the signal L2 remains at stop even after th'erelay IX becomes energized. With a train entering the approach section L3T from the right to shunt the track relay L3TR, the relay LA is deenergized and the dropping of the armature 49-into engagement with its back contact closes the circuit for the relay LH. The energizing ofthe relay LH supplies power to the circuit for the winding 5 of the mechanism a for the signal L2. However, the circuit for winding 5 is still held open at the back contact of the armature 14 of the approach locking relay LM.

The energizing-of the-relay LH lifts the armature I08 free from engagement-with its back contact toopen the stick-circuit for-the approach locking relay LM and that relay becomes deenergized as its pick-up circuit is now also open at the front contact H2 of the approach relay LA. The deenergizing of the relay LM brings about the engagement of armature 14 with its back contact which completes the circuit to: the winding 5 of the mechanism wand signal L2 is operated to display 8. proceed signal. Again it is to be noted that the approach control relay LA and the approach locking relay LM must assume their locking position against operation of switch SW before the signal L2 is permitted to display a, proceed signal, and that the clearing of the signal L2 is controlled both by the code relay IX and by the approach of the train. The closing of the contact ill of the controller 1 of the mechanism a of L2 completes the circuit for the relay LD with the result that the signal L3 is set to display a proceed signal.

' As the train advances and enters the detector track circuit IT to shunt the track relay TR the contact of the armature 54m permits the storing of a code for the reverse position of the switch after the main track routeis set up and a train has entered the approach section to clear the signal L2, without disturbing the position of the signalLZ. Let us next assume that the controlling code selects the relays BY and 'IY to permit a movement from the siding to the main line. The reversing of the switch SW brings about the reversexposition of the switch repeater relay KR and thus its armature 58 is brought into engagement with its reverse contact to close the path that extends around the normally open back contact of the armature 36 of the approach control relay RA. Under this condition the relay RH will be energized and the circuit for the winding 5 of the mechanism d at once energized to clear the signal R211.

In the event a route has been set up and a train has entered an approach track section and it then becomes necessary to change the position of the switch before the train has passed beyond the limitations of the route, the approach locking of the switch may be released by means of the time element relay TE. Assuming that the code relays GK and TY are selected to set the switch normal and to select the signal R2, and that the signal R2 .has cleared due to the fact that a train has entered the approach track section R3T, and that it then becomes necessary to change the position of the switch. The deenerigizing of the code relay 'IY causes the relay RH to be deenergized which results in the signal R2 being set at stop and the signal R3 at caution. Relay RH being down, the energizing circuit for the time element relay TE is now closed. This circuit may be traced from the positive terminal B through either the caution or stop position of the controllers for the signal R3, wire 90, armature .'9I of the relay RGP which is now energized due or to come to a stop to the rear of the signal R2.

,With armature I0 3 in engagement with its front contact, then the pick-up circuit for the approach ilocking relay RM is completed, this circuit having previously been traced, it is deemed sufficient to he r'e'point out that armature I 03 when raised closes a path around the now open front contact -.of the armature I00 of the approach control relay RA. With the approach locking relay RM energized by this pick-up circuit, its stick circuit is closed and the relay RM is retained energized in (its normal position. Theenergizing of RM permits the switch control relay W to be controlled by the code relays with the result that the position of the switch can now be selected in the usual manner. The time element relay TE functions in a like manner in connection with traflic from the right to the left.

Such a system as here provided assures that the approach control relay and the approach locking relay assume their locking position against a movement of the switch before a signal can be cleared to permit a train to pass over the ,switch. The advantage of such a positive check 'thosefamiliar with the art.

.vention, -and.modifications may be made therein within Although we have herein shown and described only one form of apparatus embodying our init is understood that various changes the scope of the appended claims without departing from the spirit and scope of our invention r .I-Iaving thus described our invention, what we claim is: a

1. In combination, a railway switch, .an approach track section, a normally energized approach control relay, a normally energized approach locking relay, a signal to govern traflic over the switch, a circuit effective to clear said signal only when said approach control relay and said approach locking relay are deenergized, means controlled from a remote point to at times deenergize said approach locking relay, and means responsive to a train entering said approach track section to deenergize said approach control relay.

2. In combination, a railway switch, an approach track section, a normally energized apsaid signal with proach control relay, a normally energized approach locking relay, a signal to govern traffic over the switch, a circuit effective to clear said signal only when said approach control relay and said approach locking relay are deenergized, means controlled from a remote point to at times deenergize said approach locking relay, means responsive to a train entering said approach track section to deenergize said approach control relay, and means to control the operation of the switch ineffective to move the switch when said relays are deenergized.

3. A centralized trafiic control system for railways including, a detector track section included in two different routes, an approach track section, a normally energized approach control relay, a normally energized approach locking re lay, a signal to govern traffic through said detector track section, a circuit efiective to clear said signal only when said approach control relay and said approach locking relay are deenergized, despatcher controlled means to deenergize said approach locking relay, a track circuit responsive to a train entering said approach track section to deenergize said approach control relay, and means to select one or the other of said difierent routes rendered inefiective to change the route when said approach locking relay is deenergized.

4. A centralized traffic control system for railways including, a detector track section included in two different routes, an approach track section, a normally energized approach control relay, a normally energized approach locking relay, a signal to govern traffic through said detector track section, a circuit effective to clear said signal only when said approach control relay and said approach locking relay are deenergized, despatcher controlled means to deenergize said approach locking relay, a track circuit responsive to a train entering said approach track section to deenergize said approach control relay, and means to select one or the other of said different routes rendered ineffective to change the route as long as either of said relays is deenergized.

5. In combination, a railway switch, a signal to govern trafiic over the switch, an approach locking means for said switch including two normally energized relays, a remote controlled circuit to govern said signal and inefiective to clear either of said relays energized, means responsive to a train approaching said signal to deenergize one of said relays, means jointly controlled by said remote controlled circuit and said first mentioned relay to deenergize the other of said relays, and means to govern the operation of the switch rendered ineffective to move said switch as long as said relays are deenergized. 1 y

6. A centralized trafiic control system for railways including, a railway switch, controlling means to control theoperation of the switch,.two normally energized approach relays, a trafiic governing circuit to govern traff c over said switch effective to permit a movementover the switch only when both of said relays are deenergized, an approach track circuit to deenergize one of said relays in response to a train approaching the switch, a despatcher controlled means to at times deenergize the other ofsaid relays, and means to render said controlling means effective tomove the switch onlycwhen said relays are energized.

7. In combination, a railway track switch, a signal for governing traflic movements over said switch, a track section in the rear of said signal, a track circuit for said section including a track relay, a signal control relay, means controlled in part by said track relay in the deenergized condition for energizing said signal control relay, 3. signal repeating relay, a circuit controlled .by said signal for energizing said signal repeating relay only if said signal is indicating stop, an approach locking rel y, a pick-up circuit for said approach locking relay closed by said tracl; relay and said signal repeating relay inv their energized condition and by said signal control relay in its deenergized condition, a stick circuit for said approach locking relay controlled by said signal control relay and by said signal repeating relay independently of said track relay, means controlled by said signal control relay in its energized condition for clearing said signal, and means controlled in part by said approach locking relay for moving said switch between its extreme positions only if said approach locking relay is energized.

. 8. In combination, a railway track switch, a signal for governing traffic movements over said switch, an approach locking relay, means controlled in part by a train approaching said signal and in part by said approach locking relay in the deenergized condition for clearing said signal, a signal repeating relay, meanscontrolled I by said signal for energizing said signal repeating relay only if said signal indicates stop, a pickup circuit for said approach locking relay closed by said signal repeating relay in the energized condition if no train is approaching within a given distance in the rear of said signal, a stick circuit for said approach locking relay closed only if said signal is controlled to indicate stop, and means controlled in part by said approach locking relay for moving said switch between its extreme positions only if said approach locking relay is energized.

9. In combination, a railway track switch, a signal for governing trafiic movements over said switch, an approach locking relay, means controlled in part by a train approaching said signal for clearing said signal, a pick-up circuitfor said approach locking relay closed by said signal in its stop condition if no train is approaching within a given distance in the rear of said signal, a stick circuit for said approach locking relay closed only if said signal is controlled to indicate stop, and means controlled in part by said approach locking relay for moving said switch between its extreme positions only if said approach locking relay is energized.

10. In combination, a railway track switch, a signal for governing trafiic movements over said switch, an approach locking relay, a normally energized approach relay deenergizable by a train approaching said signal, means controlled in part by said approach relay in its deenergized condition for clearing said signal, a pick-up circuit for said approach locking relay controlled at least in part by said approach relay in its energized condition, a stick circuit for said approach locking relay closed only if said signal is controlled to indicate stop, and means controlled in part by said approach locking relay for moving said switch between its extreme positions if said approach locking relay is energized.

11. In combination, a railway track switch, a signal for governing trafiic movements over said switch, an approach locking relay, a normally energized approach relay deenergizable by a train approaching said signal, a signal control relay, means controlled at least in part by a back contact of said approach relay for energizing said signal control relay, means controlled by a front contact of said signal control relay for clearing said signal, a pick-up circuit for said approach locking relay closed by a front contact of said approach relay if said signal control relay is deenergized, a stick circuit for said approach locking relay closed if said signal control relay is deenergized, and means controlled in part by said approach locking relay for moving said switch between its extreme positions if said approach locking relay is energized.

EARL M. ALLEN. CHARLES A. BROOKS. 

